Dell PowerConnect B-RX Configuration Manual page 428

12
SuperSpan™
Customer uses single STP but SP uses multiple spanning trees
Figure 38
SP uses multiple spanning trees.
FIGURE 38
In this setup, the customer network is running a single spanning tree for VLANs 10 and 20. The
traffic from VLAN 10 and 20 will be carried, or aggregated by VLAN 100 at the SP's network. The
main difference between this scenario and the previous two scenarios is that all traffic at the
customer's network now follows the same path, having the same STP root bridge in all VLANs.
Therefore, the customer network will not have the ability to maximize network utilization on all its
links. On the other hand, loop-free, non-blocking topology is still separately maintained by the
customer network's single spanning tree and the SP's per-VLAN spanning tree on VLAN 100.
Customer and SP use single STP
Figure 39
STP.
352
shows an example of SuperSpan where the customer network uses Single STP while the
Customer using single STP and SP using Multiple Spanning Trees
R
single
span
1/1
Customer
Region
3/1
tagged to multiple vlan
stp-boundary
untagged to vlan 100 (Super Aggregated VLAN)
shows an example of SuperSpan where the customer network and SP both use Single
R
100
2/1
Provider
Region
2/1
R
200
R
xx
Root bridge for VLAN xx
2/2
2/2
BigIron RX Series Configuration Guide
53-1002253-01